Stevenson turned up the heat at the end of the second and third quarters in Wednesday's Prospect regional semifinal boys basketball game.
Those critical runs provided the cushion the top-seeded Patriots needed to survive a 74-67 victory against No. 15 Grayslake North.
Stevenson (24-4) will take its 14-game winning streak into Friday's championship game against the winner of tonight's Prospect-Waukegan semifinal.
Grayslake North, in its first year as a Class 4A team, finishes 16-13.
Stevenson put together a 25-point second quarter that included a 7-0 burst in the last 1:06 of the half to take a 39-29 lead into halftime.
Andrew Stempel buried three 3-pointers and Jalen Brunson (game-high 32) scored 7 during the big rally.
Brunson single-handedly turned a 7-point game into a 58-45 lead with a 3-pointer and a conventional 3-point play in the last 15 seconds of the third quarter.
"The last minute of the second quarter and last 30 seconds of the third quarter were big swings," North coach Todd Grunloh said. "If you take away two minutes, we played extremely intelligent. For 30 minutes, we played well enough to win."
"We didn't play our best, but give Grayslake North credit," said Stevenson coach Pat Ambrose. "We survive and advance, but we know we're going to have to play better."
Both teams shot better than 50 percent from the field and from beyond the arc.
But at the foul line, Stevenson made 18-of-22 while North was 8-of-13.
Brunson was 10-of-11, including 9-of-10 in the fourth quarter when North was chipping away at the lead.
Led by A.J. Fish (team-best 27 points), the Knights kept it a two-possession game through the waning minutes.
Three consecutive baskets by Fish cut the lead to 4, the last coming with 50.8 seconds left at 69-65.
"We played as well as we could, but we came up short," Fish said. "We haven't played a team of this caliber all year. They're one of the best in the state.
"We knew we had a chance," Fish said. "They made their free throws to seal it."
"It's the playoffs, and they gave us their best shot," Brunson said. "We can't come out slow. We got in our groove later in the game."
Connor Cashaw scored 16 points for the Patriots and Stempel finished with 14, all in the first half.
Danny Mateling and Aidan Einloth were in double figures for the Knights with 15 points and 11, respectively.